Add bp2build support for cc_library_static.

Also refactor bp2build-related code for cc_library_headers.

(Retry of previous CL after the presubmit failed to detect a merge conflict)

Test: Added unit test.

Test: bp2build-sync.py write; bazel build //bionic/... still works (but bp2build is disabled for most cc_library_static targets for other reasons)
Change-Id: I2f4405c2fea305623bbc6daaaf62808b0c074216
diff --git a/bp2build/Android.bp b/bp2build/Android.bp
index c74f902..cc616f2 100644
--- a/bp2build/Android.bp
+++ b/bp2build/Android.bp
@@ -27,6 +27,7 @@
         "build_conversion_test.go",
         "bzl_conversion_test.go",
         "cc_library_headers_conversion_test.go",
+        "cc_library_static_conversion_test.go",
         "cc_object_conversion_test.go",
         "conversion_test.go",
         "python_binary_conversion_test.go",